EFFECTS OF BLUE-GREEN ALGAE ON SPECIFIC IMMUNITY
Hayashi et al7 examined the effect of an algae-supple-mented diet on the ability to build a specific immune response

Table 2. Immuno-Modulatory and Anti-Inflammatory Effects of Whole Blue-Green Algae

Algae Species	Introduced as:	Test Species	Effects	Reference
Spirulina sp.	Food	Human	Reversal of tobacco-induced oral cancer	Mathew et al, 1995
	Food	Mouse	Proportional reduction of IgE, increase of IgA	Hayashi et al, 1998
	Food	Mouse	Increased phagocytic activity Increased spleen cell proliferation Increased antibody production	Hayashi et al, 1994
	Food	Chicken	Increased phagocytic activity Increased NK cell-mediated anti-tumor activity Increased antibody production	Qureshi et al, 1996
	Extract	In vitro, cat	Increased phagocytic activity	Qureshi & Ali, 1996
	IP injection	Rat	Inhibition of mast cells Decrease in local allergic reaction Decrease in serum histamine levels Reduced allergy-induced mortality	Kim et al, 1998 Yang et al, 1997
Aphanizomenon flos-aquae	Food	Human	Increased transient recruitment of NK cells into tissue Increased mobilization of T and B cells into blood Mild modulation of PMN-mediated phagocytic response	Jensen et al, 2000
	Food	Rat	Decreased serum levels of arachidonic acid	Kushak et al, 2000
	Food	Rat	Source of linolenic acid (omega-3) Increased serum levels of EPA and DHA	Kushak et al, 2000
	Extract	In vitro, rat	Activation of macrophages (NF-kappaB, cytokines)	Pasco, in press

to sheep red blood cells. After immunizing mice (either once to measure the primary response or twice for the secondary response), they found that mice fed with the algae-supple-mented diet showed increased numbers of splenic IgM anti-body-producing cells when compared to control animals. Interestingly, this finding only held true for the primary immune response, as the IgG antibody production in the sec­ondary immune response was hardly affected. In experiments involving chickens, there were no differences observed in anti-sheep red blood cell antibodies during primary responses, while antibody titers for the secondary response in algae-fed chickens were augmented compared to control animals.8 The differences may reflect the anatomical differences between the rodent and chicken immune systems.

EFFECTS OF BLUE-GREEN ALGAE ON LEUKOCYTE TRAFFICKING
Much attention with regards to dietary modulation of the immune system has been given to stimulating activity of various immune cell types such as the phagocytic activity of macrophages, or the tumoricidal activity of natural killer cells. However, immune cell trafficking and the recruitment of immune cells from the systemic circulation are of equal importance. A recent study by Jensen et al5 involving

Table 3. Bio-modulatory Effects of Purified Compounds from Blue-Green Algae

Species	Compound	Effects	References
All blue-green algae	C-Phycocyanin	Anti-inflammatory (reduces leukotriene B4) Free radical scavenger Selective inhibition of COX-2 Reduced tissue damage in acetic acid-induced colitis Hepatoprotective effect	Romay 1999 Bhat & Madyastha 2000 Reddy et al, 2000 Gonzalez et al, 1999 Vadiraja et al, 1998
Spirulina	Calcium Spirulan (Ca-Sp)	Selectively inhibits penetration of virus into host cell (Herpex Simplex, human cytomegalovirus, measles, mumps, Influenza A, HIV-1)	Hayashi et al, 1996
		Reduces lung metastasis of melanoma cells by inhibition of tumor cell invasion of basal membrane	Mishima et al, 1998
	Cyanovirin-N	Irreversible inactivation of several strains of HIV (inhibited cell-to-cell and virus-to-cell fusion)	Boyd, 1997
	Extracellular products	Promotion of lactic acid bacteria growth in vitro	Parada et al, 1998
Aphanizomenon flos aquae	Unknown Polysaccharide	Induces apoptosis in some human tumor cell lines Stimulate the macrophage activity	Jensen, msp in prep Pasco et al, in press.
Lyngbya lagerheimii Phormidium tenue	Sulfolipid	Inhibits syncytium formation upon HIV infection	Gustafson et al, 1989
Phormidium tenue	Digalactosyl diacylglycerols	Inhibition of chemically induced skin tumors	Tokuda et al, 1996

humans demonstrated that the blue-green alga Aphanizomenon flos-aquae was able to trigger within two hours the migra­tion of nearly 40% of the circulating natural killer cells. This effect was significantly more pronounced in long-term consumers than in naïve subjects. In the same study, Aphanizomenon flos-aquae was also shown to stimulate the mobilization of T and B lymphocytes. This effect appeared cell-type specific since no changes were observed on poly­morph nucleated cells.

ANTI-INFLAMMATORY PROPERTIES OF BLUE­GREEN ALGAE
Blue-green algae in general contain a significant amount of carotenoids, namely beta carotene, lycopene, and lutein, providing it with good antioxidant properties. By their quenching action on reactive oxygen species, antioxi­dants carry intrinsic anti-inflammatory properties. However, blue green algae also contains specific anti­inflammatory properties as a result of their high phyco­cyanin content. Phycocyanin is a photoharvesting pigment that provides the intense blue color in blue green algae. It can constitute up to 15% of the dry weight of a blue green algae harvest. C-phycocyanin is a free radical scavenger,26 and has significant hepatoprotective effects.27 Phycocyanin was shown to inhibit inflammation in mouse ears28 and pre-tory effect seemed to be a result of phycocyanin to inhibit the formation of leukotriene B4, an inflammatory metabo­lite of arachidonic acid.28

In a study performed in rats, the blue-green algae Aphanizomenon flos-aquae was also shown to decrease the plasma level of arachidonic acid.30 Aphanizomenon flos­aquae contains significant amounts of the omega-3 alpha-linolenic acid. Omega-3 fatty acids have been shown to inhibit the formation of inflammatory prostaglandins and arachidonate metabolites. Since Spirulina contains signifi­cant amounts of omega-6 gamma-linolenic acid, the anti­inflammatory properties of Spirulina must be due to differ­ent biochemical pathways.

ANTI-VIRAL EFFECTS
As part of its program aimed at discovering new anti­tumor and anti-viral agents in natural sources, the National Cancer Institute isolated extracts of blue-green algae (Lyngbya lagerheimii and Phormidium tenue) that were found to protect human lymphoblastoid T cells from the cytopathic effect of HIV infection.  Upon further investigation, a new class of HIV inhibitory compounds called the sulfonic acid-containing glycolipids were isolated; the pure compounds were found to be strikingly active against the HIV virus in the p24 viral protein and syncytium formation assays.13 Since this discovery, there has been further investigation into other species of blue-green algae for compounds with anti-viral properties. Some compounds worthy of mention include a protein called cyanovirin-N which appears to irreversibly inactivate diverse strains of the HIV virus and to inhibit cell-to-cell and virus-to-cell fusion.14 Other studies using a water-soluble extract of blue-green algae have found a novel sulfat­ed polysaccharide, calcium spirulan (Ca-SP), to be an antivi­ral agent. This compound appears to selectively inhibit the penetration of enveloped viruses (Herpes simplex, human cytomegalovirus, measles virus, mumps virus, influenza A virus, and HIV-1) into host cells, thereby preventing replica-tion.15-17 A review of anti-HIV activity of extracts from blue-green algae has been recently published.18

ANTI-CANCER EFFECTS
An early study on bluegreen algae’s cancer-preventive properties in humans was performed on tobacco-induced oral leukoplakia.19 Mathew et al found that oral supplemen­tation with Spirulina fusiformis resulted in complete regres­sion of 57% of subjects with homogenous leukoplakia. After discontinuation of Spirulina supplementation, almost half of the complete responders developed recurrent lesions.

In other studies, extracts of bluegreen algae have been used to treat cancer in animal models. In one model, inges­tion of an extract of Spirulina and Dunaliella was shown to inhibit chemically-induced carcinogenesis in hamster buc­cal pouches.20,21 Earlier studies often attributed the anti­cancer effect of algae to its content in carotenoids since beta-carotene has been shown to have an effect similar to that of algae extract. A more recent study, however, showed that the sulfated polysaccharide mentioned above, Ca-SP, appears to inhibit tumor invasion and metastasis.22 Both the in vitro and in vivo effects of Ca-SP suggest that the intra­venous administration of Ca-SP reduces the lung metastasis of melanoma cells by inhibiting the tumor invasion of the basement membrane. A water-based extract of Aphanizomenon flos aquae containing high concentrations of phycocyanin inhibited the in vitro growth of one out of four tumor cell lines tested, indicating that at least some tumor cell types may be directly sensitive to killing by phycocyanin (Jensen et al, manuscript in preparation). Another fresh-water blue-green algae, Phormidium tenue, contains several diacyl­glycerol compounds which effectively inhibited chemical-ly-induced skin tumors in mice.23 In addition, Spirulina was shown to have a modulatory effect on hepatic carcinogen metabolizing enzymes.24

Of major interest to ongoing research in inflammation as well as breast cancer is the finding that C-phycocyanin selectively inhibits COX-2, but has no effect on COX-1.25 The COX enzymes are involved in prostaglandin synthesis. Since COX-2 is over-expressed in many breast cancer cells, and inhibition of COX-2 leads to a markedly reduced tumor growth and blocks angiogenesis, the finding that phyco­cyanin specifically interferes with this pathway holds promise.

BLUE-GREEN ALGAE AS A BIOMODULATOR
Besides their effects on the immune system, blue-green algae have also been reported to modulate other systems and improve metabolism. In the past few years increasing attention has been given to the study of the therapeutic effects of blue-green algae. The anecdotal claims for such effects are numer­ous. Although there is limited data from controlled animal or clinical studies, such claims include improvement in condition of Alzheimer’s patients, overall enhancement of immune response, improvement in fibromyalgia, control of hyperten­sion, alleviation of depression and chronic fatigue, increased stamina, healing of internal and external lesions, increased mental acuity, and general improvement in overall well-being. This last section will review the scientific evidence supporting the therapeutic effects of blue-green algae.

EFFECTS ON METABOLISM
Several reports from different labs have shown that cer­tain species of blue-green algae have cholesterol-lowering effects in animal and human models.  In feeding experiments in rats, two studies have reported that the elevation in total cholesterol, LDL, and VLDL cholesterol in serum caused by cholesterol feeding was reduced when the high cholesterol diet was supplemented with 16% and 5% blue-green algae, respectively.31,32 In addition, Kato found that adipohepatosis induced by a high fat and high cholesterol diet was cured rapidly when the diet was supplemented with algae.31 Investigations into the mechanism of this phenomenon led to the finding that the algae-fed group showed a statistically sig­nificant increase in the activity of lipoprotein lipase, a key enzyme in the metabolism of triglyceride-rich lipoproteins.33

The hypocholesterolemic effect of blue green algae was also observed in humans in a study conducted on 30 patients with mild hyperlipidemia and mild hypertension.34 Patients took 4.2 grams of algae or placebo per day, and were observed for two months. At the end of the study, patients taking the algae showed a significant reduction of LDL-cho-lesterol (p<0.05) compared to the control group. LDL cho­lesterol increased back to baseline levels after administration of the algae was discontinued. In addition to lowering LDL cholesterol levels, the atherogenic index (a measure of fat deposition in arteries) declined significantly after four weeks of algae consumption.

In a recent study by Kushak et al, rats were fed the blue-green alga Aphanizomenon flos-aquae and total cholesterol level was monitored. After 43 days, cholesterol levels were significantly decreased when compared to the control group.30 Although Aphanizomenon flos-aquae contains a significant amount of the omega-3 polyunsaturated linolenic

Table 4. Biomodulatory Effects of Whole Blue-Green Algae on Metabolism

Algae Species	Introduced as	Test Species	Effects	Reference	Effects
Aphanizomenon	Food	Rat	Reduction of cholesterol	Kushak et al, 2000	Reduction of cholesterol
	Food	Rat	Reduction of blood glucose levels	Drapeau et al, 2001	Reduction of blood glucose levels
	Food	Human	Modulation of brain activity (EEG)	Walker & Valencia, 1999	Modulation of brain activity (EEG)
Spirulina	Food	Human	Reduced body weight	Becker et al, 1986	Reduced body weight
	Food	Rat	Reduction of cholesterol	Kato et al, 1984	Reduction of cholesterol
	Food	Rat	Increased activity of lipase	Iwata et al, 1990	Increased activity of lipase
	Food	Rat	Reduced glucose levels	Takai et al, 1991	Reduced glucose levels
	Food	Rat	Inhibition of maltase and sucrase	Kushak et al, 1999	Inhibition of maltase and sucrase
	Food	Mouse	Modulation of carcinogen metabolic enzymes	Mittal et al, 1999	Modulation of carcinogen metabolic enzymes
	Food	Mouse	Modulation of lead toxicity	Shastri et al, 1999	Modulation of lead toxicity
	Food	Rat	Increased iron status during pregnancy and lactation	Kapoor & Mehta, 1998	Increased iron status during pregnancy and lactation
Nostoc	Food	Rat	Reduction of cholesterol	Hori et al, 1994	Reduction of cholesterol

acid, the effect on cholesterol levels seemed unrelated to the lipid content of the diets. Kushak et al30 proposed that the hypocholesterolemic effect of Aphanizomenon flos-aquae may be due to its chlorophyll content which was shown to stimulate liver function and decrease blood cholesterol.35

In a double-blind crossover study involving human patients, supplementing the diets of obese outpatients with 2.8 grams of bluegreen algae three times daily over a four week period resulted in a statistically significant reduction of body weight.36 In a study measuring the effect of bluegreen algae on glucose levels in diabetic rats, the water-soluble fraction was found to be effective in lowering the serum glucose level at fasting, while the water insoluble fraction suppressed glu­cose levels at glucose loading.37 In another study investigating the effect of the blue-green alga Aphanizomenon flos-aquae on rat intestinal mucosal digestive enzymes, it was observed that this alga specifically inhibited the activity of maltase and sucrase in a dose-dependent manner.38 Furthermore, this decrease in enzymatic activity was accompanied by a dose-dependent decrease in blood glucose.

The overall conclusion is that blue-green algae may have benefits on lipid and sugar metabolism, as well as liver function. Further human studies are needed to address the feasibility of using blue-green algae in conjunction with cholesterol-lowering medication.

OTHER EFFECTS OF BLUE GREEN ALGAE
Other research studies on blue green algae consumption deserve mention. Many reports exist in the literature on its antimicrobial effects.  The secretion of anti-microbial sub­stances is an important part of the competition for ecological niches in the natural environment. However, an interesting caveat exists. In one study, Spirulina was cultured in vitro, and the extracellular medium was shown to stimulate the growth of lactic acid bacteria.39 If the growth-promoting sub-stance(s) exist in sufficient amounts intracellularly, blue green algae may play a role in vivo by supporting friendly gut bacteria. This leads to other facets of health including gut health and nutrient absorption. On that note, consumption of Spirulina was shown to support the iron status and hemoglo­bin of rats during pregnancy and lactation.40 Spirulina fusiformis had a significant protective effect against lead-induced toxicity in rats.41 Finally, a report by Valencia et al has presented evidence that Aphanizomenon flos-aquae accelerates recovery from mild traumatic brain injury.42

CONCLUSION AND SUMMARY
Research results based on the numerous isolated com­pounds from blue green algae warrant the exploration of using whole algae as conjunctive therapy due to the possible synergistic effects of many phytochemicals within the whole algae. The emergence of composite algae supple­ments in contrast to single algae supplements may also yield further anti-inflammatory, immune-boosting, and metabolic benefits. A significant body of data suggests that blue green algae immunoenhancing properties could be useful in the adjunct treatment of various diseases involving 1) sup­pressed or exhausted immune system, and 2) inappropriate immune response including allergies, autoimmune diseases, and chronic inflammatory conditions. The data presented also suggests that blue green algae could be useful as an adjunct in the treatment of cancer and AIDS, and calls for the design of controlled human clinical studies.

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Winter 2001 Vol. 3, No. 4  JANA  28

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